Overview Information

Niacin is a form of vitamin B3. It is found in foods such as yeast, meat, fish, milk, eggs, green vegetables, and cereal grains. Niacin is also produced in the body from tryptophan, which is found in protein-containing food. When taken as a supplement, niacin is often found in combination with other B vitamins.

Do not confuse niacin with niacinamide, inositol nicotinate, IP-6, or tryptophan. See the separate listings for these topics.

Niacin is taken by mouth for high cholesterol and other fats. It is also used for low levels of a specific type of cholesterol, HDL. It is also used along with other treatments for circulation problems, migraine headache, Meniere's syndrome and other causes of dizziness, and to reduce the diarrhea associated with cholera. Niacin is also taken by mouth to for preventing positive urine drug screens in people who take illegal drugs.

Niacin is taken by mouth for preventing vitamin B3 deficiency and related conditions such as pellagra. It is also taken by mouth for schizophrenia, hallucinations due to drugs, Alzheimer's disease and age-related loss of thinking skills, chronic brain syndrome, muscle spasms, depression, motion sickness, alcohol dependence, blood vessel swelling linked with skin lesions, blocked blood vessels in the eye, and fluid collection (edema).

Some people take niacin by mouth for acne, leprosy, attention deficit-hyperactivity disorder (ADHD), preventing premenstrual headache, improving digestion, protecting against toxins and pollutants, reducing the effects of aging, arthritis, lowering blood pressure, improving circulation, promoting relaxation, improving orgasms, and preventing cataracts. It is also used to improve exercise performance.

How does it work?

Niacinamide can be made from niacin in the body. Niacin is converted to niacinamide when it is taken in amounts greater than what is needed by the body. Niacin and niacinamide are easily dissolved in water and are well-absorbed when taken by mouth.

Niacin and niacinamide are required for the proper function of fats and sugars in the body and to maintain healthy cells. At high doses, niacin and niacinamide can have different effects. Niacin might help people with heart disease because of its beneficial effects on clotting. It may also improve levels of a certain type of fat called triglycerides in the blood. Niacinamide has no beneficial effects on fats and should not be used for treating high cholesterol or high fat levels in the blood.

Niacin deficiency can cause a condition called pellagra, which causes skin irritation, diarrhea, and dementia. Pellagra was common in the early twentieth century, but is less common now, since foods are now fortified with niacin. Pellagra has been virtually eliminated in western culture.

People with poor diet, alcoholism, and some types of slow-growing tumors called carcinoid tumors might be at risk for niacin deficiency.

Uses & Effectiveness?

Likely Effective for

High cholesterol. Only niacin seems to lower cholesterol, not niacinamide. Some niacin products are FDA-approved prescription products for treating high cholesterol. These prescription niacin products typically come in high strengths of 500 mg or higher. Dietary supplement forms of niacin usually come in strengths of 250 mg or less. Since very high doses of niacin are required for high cholesterol, dietary supplement niacin usually isn’t appropriate.

Treatment and prevention of niacin deficiency, and certain conditions related to niacin deficiency such as pellagra. Both niacin and niacinamide are approved by the U.S. Food and Drug Administration (FDA) for these uses. Niacinamide is sometimes preferred because it doesn’t cause “flushing,” (redness, itching and tingling), a side effect of niacin treatment.

Possibly Effective for

Hardening of the arteries (atherosclerosis). Taking niacin by mouth along with medicines called bile acid sequestrants seems to reduce hardening of the arteries in men with this condition. It seems to work best in people with high levels of blood fats called triglycerides prior to treatment. Taking niacin with cholesterol-lowering medications also seems to reduce the risk of adverse heart-related adverse events in people with a history of narrowing or hardening of the arteries. But taking niacin does not seem to reduce hardening of the arteries in patients with a condition called peripheral arterial disease (PAD).

Diarrhea from an infection called cholera. Taking niacin by mouth seems to control the loss of fluid due to cholera.

Abnormal levels of blood fats in people with HIV/AIDS. Taking niacin seems to improve levels of cholesterol and blood fats called triglycerides in HIV/AIDS patients with abnormal blood fat levels due to antiretroviral treatment.

Metabolic syndrome. Taking niacin seems to increase levels of high-density lipoprotein (HDL or "good") cholesterol and reduce levels of blood fats called triglycerides in people with metabolic syndrome. Taking the niacin along with a prescription omega-3 fatty acid seems to work even better.

Insufficient Evidence for

Alzheimer's disease. People who consume higher amounts of niacin from food and multivitamins seem to have a lower risk of getting Alzheimer's disease than people who consume less niacin. But there is no evidence that taking a stand-alone niacin supplement helps to prevent Alzheimer's disease.

Cataracts. Taking niacin by mouth might reduce the risk of nuclear cataracts. Nuclear cataract is the most common type of cataract.

Erectile dysfunction. Taking extended-release niacin seems to help men with erectile dysfunction maintain an erection during sexual intercourse.

Exercise performance. Research shows that taking a supplement containing niacin and other ingredients before exercise does not improve performance during exercise in men.

High levels of phosphate in the blood (hyperphosphatemia). High blood levels of phosphate can result from kidney dysfunction. Some early research shows that taking niacin by mouth can reduce blood levels of phosphate in people with end-stage kidney disease and high levels of blood phosphate. But other research shows that taking niacin by mouth at a higher dose does not lower blood phosphate levels when taken along with medication used to lower blood phosphate levels.

Blockage of the vein in the eye (retinal vein occlusion): Early research shows that taking niacin might improve eyesight in people with a blockage in the retinal vein.

Sickle cell disease: Early research shows that taking niacin does not improve the levels of blood fats in people with sickle cell disease.

Side Effects & Safety

Niacin is LIKELY SAFE for most people when taken by mouth. A common minor side effect of niacin is a flushing reaction. This might cause burning, tingling, itching, and redness of the face, arms, and chest, as well as headaches. Starting with small doses of niacin and taking 325 mg of aspirin before each dose of niacin will help reduce the flushing reaction. Usually, this reaction goes away as the body gets used to the medication. Alcohol can make the flushing reaction worse. Avoid large amounts of alcohol while taking niacin.

Other minor side effects of niacin are stomach upset, intestinal gas, dizziness, pain in the mouth, and other problems.

When doses of over 3 grams per day of niacin are taken, more serious side effects can happen. These include liver problems, gout, ulcers of the digestive tract, loss of vision, high blood sugar, irregular heartbeat, and other serious problems.

When used daily for multiple years, niacin might increase the risk of developing diabetes.

Some concern has been raised about stroke risk in people taking niacin. In one large study, people who took high doses of niacin had a two-fold greater risk of stroke compared to those not taking niacin. However, it is unlikely that this outcome was due to niacin. Most experts believe that it is too soon to draw any conclusions about niacin and strokes.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Niacin is LIKELY SAFE for pregnant and breast-feeding women when taken in the recommended amounts. The recommended amount of niacin for pregnant or breast-feeding women is 30 mg per day for women under 18 years of age, and 35 mg for women over 18.

Interactions?

Moderate Interaction

Be cautious with this combination

!

Alcohol (ethanol) interacts with NIACIN AND NIACINAMIDE (VITAMIN B3)

Niacin can cause flushing and itchiness. Consuming alcohol along with niacin might make the flushing and itching worse. There is also some concern that consuming alcohol with niacin might increase the chance of having liver damage.

Carbamazepine (Tegretol) is broken down by the body. There is some concern that niacinamide might decrease how fast the body breaks down carbamazepine (Tegretol). But there is not enough information to know if this is important.

Some medication for lowering cholesterol called bile acid sequestrants can decrease how much niacin or niacinamide the body absorbs. This might reduce the effectiveness of niacin or niacinamide. Take niacin or niacinamide and the medications at least 4 hours apart.<br /><br />
Some of these medications used for high cholesterol include cholestyramine (Questran) and colestipol (Colestid).

Medications used for lowering cholesterol (Statins) interacts with NIACIN AND NIACINAMIDE (VITAMIN B3)

Niacin can adversely affect the muscles. Some medications used for lowering cholesterol called statins can also affect the muscles. Taking niacin along with these medications for lowering cholesterol might increase the risk of muscle problems.<br /><br />
Some of these medications used for high cholesterol include rosuvastatin (Crestor), atorvastatin (Lipitor), lovastatin (Mevacor), pravastatin (Pravachol), and simvastatin (Zocor).

Primidone (Mysoline) is broken down by the body. There is some concern that niacinamide might decrease how fast the body breaks down primidone (Mysoline). But there is not enough information to know if this is important.

Probenecid interacts with NIACIN AND NIACINAMIDE (VITAMIN B3)

Probenecid is used to treat gout. Taking large doses of niacin might worsen gout and decrease the effectiveness of probenecid.

Sulfinpyrazone (Anturane) is used to treat gout. Taking large doses of niacin might worsen gout and decrease the effectiveness of sulfinpyrazone (Anturane).

Minor Interaction

Be watchful with this combination

!

Aspirin interacts with NIACIN AND NIACINAMIDE (VITAMIN B3)

Aspirin is often used with niacin to reduce the flushing caused by niacin. Taking high doses of aspirin might decrease how fast the body gets rid of niacin. This could cause there to be too much niacin in the body and possibly lead to side effects. But the low doses of aspirin most commonly used for niacin-related flushing don't seem to be a problem.

Niacin can sometimes cause flushing and dizziness. The nicotine patch can also cause flushing and dizziness. Taking niacin and/or niacinamide (vitamin B3) and using a nicotine patch can increase the possibility of becoming flushed and dizzy.

Dosing

The following doses have been studied in scientific research:

ADULTS

BY MOUTH:

For high cholesterol:The effects of niacin are dose-dependent. Doses of niacin as low as 50 mg and as high as 12 grams each day have been used. However, the biggest increases in HDL and decreases in triglycerides occur at 1200 to 1500 mg/day. Niacin's greatest effects on LDL occur at 2000 to 3000 mg/day. Niacin is often used with other medications for improving cholesterol levels.

For preventing and treating vitamin B3 deficiency and related conditions such as pellagra: 300-1000 mg daily in divided doses.

For treating hardening of the arteries: Doses of niacin have been as high as 12 grams daily. However, a dose of about 1 to 4 grams of niacin daily, alone or along with statins or bile acid sequestrants (a cholesterol-lowering medicine), has been used for up to 6.2 years.

For abnormal blood fat levels due to treatment for HIV/AIDS: Up to 2 grams daily has been used.

For metabolic syndrome: 2 grams of niacin has been taken daily for 16 weeks. In some cases, niacin 2 grams daily, alone or at this dosage, is taken along with 4 grams of prescription omega-3 ethyl esters (Lovaza, GlaxoSmithKline Pharmaceuticals).

BY IV:

For preventing and treating vitamin B3 deficiency and related conditions such as pellagra:
60 mg of niacin has been used.

AS A SHOT:

For preventing and treating vitamin B3 deficiency and related conditions such as pellagra:
60 mg of niacin has been used.

CHILDREN

BY MOUTH:

For preventing and treating vitamin B3 deficiency and related conditions such as pellagra: 100-300 mg per day of niacin, given in divided doses.

CONDITIONS OF USE AND IMPORTANT INFORMATION:
This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.